import com.mysql.jdbc.jdbc2.optional.MysqlDataSource;
import javax.sql.DataSource;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;

public class DBUtil {
    private static String URL = "jdbc:mysql://127.0.0.1:3306/database1?characterEncoding=utf8&useSSL=false";
    private static String USERNAME = "root";
    private static String PASSWORD = "root";

    private static volatile DataSource dataSource = null;

    private static DataSource getDataSource(){
        if (dataSource == null){
            synchronized (DBUtil.class){
                if (dataSource == null){
                    dataSource = new MysqlDataSource();
                    ((MysqlDataSource) dataSource).setURL(URL);
                    ((MysqlDataSource) dataSource).setUser(USERNAME);
                    ((MysqlDataSource) dataSource).setPassword(PASSWORD);
                }
            }
        }
        return dataSource;
    }
    public static Connection getConnection() throws SQLException {
        return getDataSource().getConnection();
    }
    public static void close(Connection connection, PreparedStatement statement,
                             ResultSet resultSet) {
        try {
            if (resultSet != null) {
                resultSet.close();
            }
            if (statement != null) {
                statement.close();
            }
            if (connection != null) {
                connection.close();
            }
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }
}
